Nick Turner, TDC’s cabinet member for environment and coast protection, said: “We now need to move in and decide what measures we need to take to ensure the safety of all those who use the beaches.

“Although we do not want to close beaches to the public in the summer we will not hesitate to do so if that is the advice we are given.”

He added that the matter was being taken very seriously and people’s safety would always be put first and not compromised in any way.

It is believed that the grenades may have been exposed following high winds and tidal movements.

Three wartime grenades were discovered and blown up by bomb disposal experts on the beach at Dovercourt on July 12.

The temporary signs will be replaced with permanent ones.

Captain Nick Mathieson, of Colchester Troop, 621 Squadron, 11 Explosive Ordnance Disposal Regiment, The Royal Logistic Corps, said: “We would encourage people to call 999 if they have concerns about any suspect items they find and not to touch them. It is better to be safe than sorry.”